Penso che balancor in realtà stia per balancer. Infatti da http://www.springerlink.com/content/m358v321t7w4484l/ :

"Soft-tissue alignment of the knee is important in total knee replacement. Achieving perfectly aligned and well-balanced soft tissues is more difficult than achieving good bony alignment. A mechanical **balancer/tensiometer** is an invaluable tool for this purpose and should be available to any surgeon performing knee arthroplasty."

Qui il tensiometro è usato proprio in artroscopia sul ginocchio:

http://www.giomi.it/Portals/0/giomi/images/stories/Pubblicaz...

(Si parla anche di "bilancio artroscopico", se può aiutare.)